Routing Table Related Questions

[Translator]

Testing with Loopback in a Pnet environment.

The routing of the Switch5 is set as below.

ip route 2.2.2.2 255.255.255.255 192.168.1.2
ip route 2.2.2.2 255.255.255.255 192.168.1.3 10
Go!
The other two routes were set to Default G/W at 192.168.1.1

In the above situation, I Shudown gi0/0 interface of SW5.

Port Name Status Vlan Duplex Speed Type
Gi0/0 disabled 10 auto auto RJ45
Gi0/1 connected 10 a-full auto RJ45
Gi0/2 notconnect 1 a-full auto RJ45
Gi0/3 notconnect 1 a-full auto RJ45
Gi1/0 notconnect 1 a-full auto RJ45
Gi1/1 notconnect 1 a-full auto RJ45
Gi1/2 notconnect 1 a-full auto RJ45
Gi1/3 notconnect 1 a-full auto RJ45

sw5#show ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override

Gateway of last resort is not set

1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.1.1.0/24 is directly connected, Loopback0
L 1.1.1.1/32 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
S 2.2.2.2 [1/0] via 192.168.1.2
192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.1.0/24 is directly connected, Vlan10
L 192.168.1.1/32 is directly connected, Vlan10

In the above situation, when ICMP was blown from Sw5 with Src 1.1.1.1 Des 2.2.2.2, it was expected to be Drop, but communication was performed normally.

Although it is stated to be 2.2.2.2.2 next-hop 192.168.1.2 under the routing table, we do not understand why it was communicated through 192.168.1.3 which is not listed on the table... 

Can you share what I don't know? 

[paul driver]

Hello

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@Translator wrote:

Although it is stated to be 2.2.2.2.2 next-hop 192.168.1.2 under the routing table, we do not understand why it was communicated through 192.168.1.3 which is not listed on the table... 

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The reason is only the active most preferred static (lower admin distance) is entered in the route table

[Translator]

Which command should I use to view the table of 192.168.1.3?

[MHM Cisco World]

SW6'7 both advertise same LO 2.2.2.2

So SW5 have two path to 2.2.2.2

It seen that traffic pass to other SW 

Use traceroute to check

[supunit21]

Hello,

Both ports (Gi0/0 and Gi0/1) on SW5 belong to the same VLAN (VLAN-10).

Even though you shut down the Gi0/0 port, there is still one port active in the VLAN-10 (Gi0/1). Which means switch still thinks it can reach the preferred next hop 192.168.1.2 via Gi0/1. SW5 will not flush out the preferred static route pointing to 192.168.1.2 from its routing table in this case. 

This is expected behavior.